A method and arrangement for the information of mobile subscribers are described in PCT International Patent Publication No. WO 98/26396. In that case, data is transmitted in response to inquiry and/or automatically between a central unit and a mobile subscriber unit. This data is intended to be used in particular to transmit traffic information to the mobile subscriber. In principle, this can be done in two ways. On the one hand, all information concerning traffic routing is given to the mobile subscriber from the center (central unit), so that the road-user is completely dependent on the information from the center. The other possibility is for the road-user to carry a navigational unit with him in his vehicle, by which it is possible to obtain a traffic route from the given position at the moment to a destination position. In this case, the center is only used to have such traffic information transmitted which could lead to an obstruction of the journey, in particular traffic jams, roadblocks, detours or weather-contingent disturbances. This information can either be transmitted in plain text, or else in a reduced form, only codes being transmitted and these codes than being combined in the receiver to form complete messages. Such a measure is described, for example, in German Patent No. 35 36 820. A transceiver which permits both the transmission and the reception of messages must be provided for each subscriber in order to dispatch and receive information. For example, such a transceiver can be a customary mobile transceiver, but there can also be transmitters which transmit information on a specific frequency to a center, and radio receivers, for example, which are able to receive individualized messages. In this case, after processing the query, the center can then broadcast the information via a broadcast transmitter and, on the basis of the individual identifier, can assure that only the receiver which is individualized correspondingly is able to interpret the message.
According to the present invention, on the basis of the information transmitted to the center, it is ensured that the coded traffic messages can at all events also be interpreted in the vehicle, since the transmitted version identifier ensures that the information transmitted back from the center can also be interpreted in the vehicle with the data existing there. Misinformation or false information which relates to false or missing versions of the stored data is thereby reliably avoided.
It is advantageous that a plurality of data groups for different geographical regions are stored in the memory. This measure makes it possible for the vehicle having the device to interpret and process coded transmitted traffic messages in a larger geographical region, i.e., in France, Great Britain, and in the Benelux countries as well, in addition to Germany. Another advantage is that a plurality of data groups having different details are stored in memory for a geographical region. This measure ensures that, for example, further and more detailed information is made available for specific regions such as large cities or regions of interest to tourists. In response to a request for traffic information, this detailed information at hand can be taken into account in a response from the base station.
It is also beneficial that the version and/or the manufacturer and/or the issue date, also denoted as data-group information, are transmitted in the traffic query, separately for each data group. These measures ensure that, for example, even when the stored data is expanded by complementary purchase, such as regionally, evaluable traffic information is always made available, regardless of how old the stored data is with respect to the different regions.
Furthermore, it is advantageous, along with the traffic-information query, to transmit information as to whether the radio receiver having the navigational device is able or not to evaluate several data groups simultaneously. Particularly in the case of simple devices, there is the problem that traffic messages can only be evaluated utilizing one data group. It is therefore not sensible if, during a transmission, traffic information is transmitted from the base station which requires several data groups for the evaluation, since then an evaluation in a predefined reaction time is no longer possible. In this case, only such information is sent back from the base station which is evaluable using one data group.
It is also advantageous that the traffic-information query is sent in response to prompting. Because of this, it is up to the user as to how frequently he would like to request traffic messages. Particularly when, after a query, he determines that traffic obstructions are not to be anticipated, often new queries are first really necessary after a longer driving time. Therefore, the user of the device is able to transmit queries according to his wishes.
It is also expedient to request the traffic information at predefined time intervals. The driver of a vehicle is relieved by this measure. He does not always have to think whether a new traffic message is necessary. Rather, an inquiry about traffic obstacles is made as a function of the route being traveled on, or according to time-related defaults, so that the driver is constantly informed about up-to-date traffic events, particularly about new obstacles on the roads, without he himself having to think about it.
It is also advantageous to calculate a route from a present point to a destination point based on the received traffic information. In so doing, the information about the traffic jams and obstructions, transmitted based on the traffic query, is taken into account when determining the route. It is also advantageous not to transmit all the traffic information corresponding to the query criteria, but rather only such traffic information lying in (pertaining to traffic conditions in) a predefined corridor between the present point and the destination point. In this manner, the number of traffic messages is further restricted, it being necessary to take heed that the corridor is selected in such a way that possible and useful bypass roads are also determined.
It is likewise beneficial that, given the evaluation possibility of a plurality of data groups in the transceiver or the navigation device, the location code is transmitted together with the version from the base station. In this manner, even in the case of expanded geographical regions such as Germany and France, the location is clearly allocated, so that French locations are allocated to the French data group and German locations are allocated to the German data group.